JPS5837148B2 - Method for preventing adhesion of unvulcanized chloroprene rubber chips - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing adhesion of chips of unvulcanized chloroprene rubber having rubber-like elasticity.

Chloroprene rubber is normally cut into chips in the final manufacturing process, supplied to consumers in the form of chips, and subjected to subsequent processing, vulcanization, and molding steps.

The shape of the chip is, for example, often a flat piece with a cross section of about 10 to 20 mm in the minor axis, about 30 to 40 mm in the major axis, and about 5 to 15 mm in thickness.

Manufactured unvulcanized chloroprene rubber chips are usually packaged in bags and supplied to consumers or processing plants, where they are used in the required amount. The same is true for plastic materials.

There are two types of unvulcanized chloroprene rubber: soft ones with high rubber-like elasticity and so-called hard ones with low rubber-like elasticity. Since the chips tend to stick to each other, it is an object of the present invention to provide a method for preventing such sticking.

In other words, when the chips packed in bags are stored (including transportation) as described above, the bags are naturally piled up, but the ones at the bottom are loaded, and the chips are crushed and crushed. The new surfaces produced by the compression and expansion come into strong contact with each other, so they easily stick together and form into lumps, making it difficult to handle and take out the required amount.

The present invention aims to eliminate these difficulties.

As a measure to prevent chips from sticking, it is common practice to coat the chips with an anti-stick powder to prevent chips from coming into direct contact with each other.

Talc, calcium carbonate, perlite and sonoike inorganic powders are used as anti-adhesive powders, and talc will be described below as a representative example.

The method of sprinkling chips with talc simply involves adding talc to the chips and mixing them, so since the talc is only on the chip surface, it is easy to peel off, especially for chips with flat-cut surfaces. However, since the surface is clean and smooth, the talc peels off more easily and is not useful for preventing direct contact between chips.

In the case of such a simple talc mixing method, the talc that is initially added and mixed and adheres to the surface of the inner chips and serves to prevent direct contact between the chips accounts for only 1/2 of the total amount of talc present in the bag. Approximately 2 to 1/3 of the talc does not unravel, and the remaining part peels off from the chip surface and unnecessarily becomes unevenly distributed at the bottom or top of the bag as so-called excess talc. When the bag is opened, it becomes dust and scatters, significantly polluting the working environment. lead to worse results.

Conventionally, attempts to solve this problem have been made by passing the chip through a contact tank made of a dispersion of talc and water to which a small amount of adhesive such as rubber latex has been added, and then air-drying the chip, or by applying a silicone solution to the chip surface in advance. A method of adding talc after coating it on top has been proposed.

However, these methods use chemicals, are complicated to operate, tend to be expensive, and in comparison, the adhesion of talc is weak, and the anti-adhesive effect cannot be said to be sufficient.

The present invention is not a method of attaching an anti-adhesive powder to the chip surface through a layer of an adhesive substance, but a method of mechanically holding the powder firmly against the chip, thereby preventing the chip from adhering. Yes, and the effects are very good.

The method of the present invention will be explained in detail below.

The present invention provides a method for compressing unvulcanized chloroprene rubber chips having rubber-like elasticity to a thickness corresponding to or less than the thickness at which the chips are crushed in the flat direction under conditions of accumulation and storage, and at the same time powdering an anti-adhesive powder. The powder is uniformly dispersed and pressed onto the surface of the pressure-biased chip, and when the chip is released from the pressure-biased state, the powder is partially embedded in the chip surface and in the inner layer adjacent to the surface. This is a method for preventing adhesion of unvulcanized chloroprene rubber chips, which is characterized in that the chips are held in an embedded state.

According to the method of the present invention, the powder is not simply sprinkled on the surface of the chip, but is simultaneously distributed and compressed when the chip is mechanically compressed. It is held in an embedded state and therefore does not peel off easily.

Furthermore, the chips are mechanically compressed to a thickness equal to or less than the thickness at which they would actually be crushed under deposition and storage conditions, and the powder is dispersed and supplied thereto to compress them.
When the chip, which has been temporarily biased, is released from the biased state, the powder is also trapped and embedded in the inner layer adjacent to the surface of the chip.

Therefore, even if such chips are crushed under pressure during storage and the inner layer near the surface newly appears on the surface layer, the powder embedded therein will effectively prevent the chips from sticking together. fulfill the role of

In the case of the conventional method, even if anti-adhesive powder is present on the surface of the chip before being crushed, once the chip is crushed and a new inner layer appears on the surface, the newly formed surface will no longer be coated with anti-adhesive powder. There are no particles or powder present, which results in the chips easily sticking together.

However, according to the present invention, effective prevention of adhesion can be achieved even in such cases.

This is one of the most important effects of the present invention.

The chips that have undergone the above-described mechanical compression and powder compression operations according to the present invention can be subjected to, for example, a sieve to separate excess powder, if necessary.

Of course, at this time, the powder embedded in the surface and inner layer of the chip does not come off.

Further, since separation does not occur during storage, transportation, etc., almost no free talc is generated unlike in products made by the conventional powder mixing and sprinkling method, and therefore there are no problems such as deterioration of the working environment due to dust scattering.

The rubber-like elasticity of chloroprene rubber varies depending on the grade, but the higher the elasticity and the softer the rubber, the more it is appropriate to repeat the pressure biasing and crimping operations described above.

This is based on the fact that the softer the material, the more likely the crushing direction will change due to changes in load during storage or transportation, and a new inner layer may come to the surface.

The chloroprene rubber targeted in the method of the present invention has a JIS standard hardness (K6300, K6301, physical property test method for unvulcanized and vulcanized rubber) when kept at -10°C for 200 hours. Those whose rise is within 50 degrees are preferably used.

In the case of such chloroprene rubber, it has been found that it is necessary to repeat the pressing and powder pressing operations at least three times in order to achieve the desired anti-stick properties of one chip.

An example of a specific embodiment of the method of the present invention will be described below with reference to the accompanying drawings.

The accompanying drawing (FIG. 1) is a schematic diagram for explaining a mode in which chip pressure biasing and talc crimping operations are performed three times in succession according to the method of the present invention.

1 in the figure is the storage of chips made in the final process of chloroprene rubber production.

The chips are conveyed by a chute to a mixing device 2 with talc.

The mixing device 2 is an ordinary mixer equipped with a stirrer that can sufficiently add and mix talc to chips while supplying talc from a talc supply hopper 3.

Reference numeral 4 denotes a chip feeder, which supplies the chips to the biasing rolls 5, 6, 7, and 8 without overlapping each other when the chips pass through the biasing rolls 5, 6, 7, and 8.

Due to this feeder 4, the flat chips slide onto the surface of the roll 5 in a shape as if coins were lined up vertically on a plane.

5 and 6 form the first-stage compacting rolls, 5 and 7 form the second-stage compacting rolls, and 7 and 8 form the third-stage compacting rolls, and the chips are compacted to a predetermined thickness at each stage. Then, the loop supplied from the loop hopper 3 is crimped.

It is preferable that the roll surface is provided with appropriate incisions, such as mesh-like incisions of 1 to 2 m/m, so as to sufficiently retain the talc.

In this way, the chips that have been compressed by the 1st, 2nd and 3rd stage pressure biasing rolls and have had enough talc adhered to them are passed through the sieving machine 9 as necessary.
Excess talc that is not embedded in the chip surface is screened out.

The sieved talc is returned to the first talc supply hopper 3 by the conveyor 10 and can be reused.

The chips from which excess talc has been separated are sent to the next process such as packaging and storage.

A specific example of the present invention will be explained by the following example.

The percentages listed are by weight.

Example: The sample chloroprene rubber used is a type with high rubber-like elasticity, i.e., a chip with a JIS hardness increase of 15 degrees after being kept at an environmental temperature of -10'C for 200 hours, was subjected to the following pressure polarization and talc crimping operations. I was made to obey.

The shape of the tip is about 33 to 37 mm long axis and about 15 mm short axis.
It was oval in shape and had a door about 5 to 7 meters thick.

The gap between the pressure rolls is approximately 850 mm, which is the most severe condition normally assumed when bagged chip products are piled and stored.
2 m, corresponding to the thickness when the chip is crushed under a pressure of 2 to 31 n7IL at a pressure of 2 m
Adjusted to m.

The chips were passed through the pressure roller 1 to 5 times while uniformly distributing and supplying talc onto the surface of the chips.

As a comparative example, a test was conducted using the conventional method of simply sprinkling talc.

Amount of talc supplied (relative to chip weight, %) in each test
Table 1 shows the amount of talc deposited on the chip surface (same as above).

In the examples of the present invention, excess talc was separated by sieving.

Each sample obtained in the test was packed in a bag, and 30 to 3
It is deposited in a constant temperature chamber held at 2°C, compressed and kept at the bottom for two cycles by applying a pressure of approximately 850 kg/d.
Each product was then evaluated for its degree of anti-sticking.

The determination results are shown in Table 1.

The degree of prevention of adhesion between chips is very good, good, slightly good,
Classified as defective or unacceptable.

The degree of anti-sticking can be expressed empirically by classifying the state into several degrees.

Here, "Extremely good 0" means that many chips are completely separated and independent from each other, and "11 not good" means that the chips are completely sticky and form a block like a monolith. Indicates a state in which it is impossible to fold or break.

Between these two extreme states, there are good, somewhat good, and poor states.

"1 Good" means that even if the chips are assembled, they can be loosened with fingers without using much force, or that they can be crushed by hand and easily separated into individual chips.

II Defective "1" means that the stickiness has further progressed and it is impossible to separate the chips into individual chips even if pulled by hand, and if you try to make them smaller, the board will break.

These results show that the sample subjected to pressure polarization and talc compression according to the present invention has a superior anti-adhesive effect compared to the conventional method.

Similar results were also obtained for chips with a value of 10 degrees.

In particular, in the case of rubber chips with high rubber-like elasticity such as those used in the test, it is clear that the effect sharply increases when the operation according to the present invention is repeated three times.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an example of an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. Unvulcanized chloroprene rubber chips having rubber-like elasticity are compressed to a thickness corresponding to or less than the thickness at which the chips are crushed under pile storage conditions, and at the same time anti-stick powder is applied. The powder is uniformly dispersed and pressed onto the surface of the pressure-biased chip, and when the chip is released from the pressure-biased state, the powder is partially embedded in the chip surface and in the inner layer adjacent to the surface. A method for preventing adhesion of unvulcanized chloroprene rubber chips, characterized in that the chips are held in an embedded state. 2. Chips of unvulcanized chloroprene rubber having rubber-like elasticity with an increase in JIS hardness of within 50 degrees after being kept at -10°C for 200 hours are subjected to the pressure polarization and anti-sticking powder uncrimped operation for at least 3 hours. 2. The method according to claim 1, wherein the method comprises dispensing.